Abstract:

To calculate the phase shift, zero-crossing detection, digital correlation method and FFT are commonly used. Tests on the three algorithms show that, they can obtain phase shift accurately in dozens of microseconds delay, but resources and time cost are different. Zero-crossing detection needs more resources, but less time. FFT has large resource occupancy and latency. Digital correlation method is just the opposite to FFT, but detecting phase reverse is difficult.

Key words: Phase shift, Zero-crossing detection, Digital correlation method, FFT, NI FlexRIO, LabVIEW FPGA

摘要：

介绍了常用的相位差算法过零检测法、数字相关法和FFT 算法，对这三种算法的测试表明，三者均能在几十微秒量级的延时内较准确地获得计算结果，但所需的资源和时间开销有所不同。过零检测法占用的资源较多，但平均计算延时较小；FFT 资源占用率和延时均较大；而数字相关法资源占用率和延时均较小，但相位翻转的判断存在困难。

关键词: 相位差, 过零检测法, 数字相关法, FFT, NI FlexRIO, LabVIEW FPGA